Israel Strikes Meant to Thwart Iran’s Influence in Syria

The U.S. and Israel are concerned about Iran’s exploitation of the instability of Syria’s seven-year war to spread its influence, with officials saying they see its activities there as part of Iran’s efforts to project power in the wider region.

Israel’s military wants to prevent Tehran from building up military capabilities in Syria comparable to those in neighboring Lebanon, where it has nurtured the Shiite militia Hezbollah and helped it confront Israel militarily, according to

Amos Yadlin,

a former head of Israeli military intelligence.

“They will not let them duplicate Hezbollah,” he said. “They will not let them have an advanced military capability in Syria.”

The small scale of the attacks against Israel suggests Tehran isn’t at this point inclined to provoke a bigger war. Iran didn’t use its most advanced missiles, according to

Michael Horowitz,

an analyst at Le Beck International, a security and risk management firm.

By contrast, Israel’s escalation was designed to convey to Tehran, and its ally Russia, “about the need to rein in Iran or face the threat of a broader conflict,” Mr. Horowitz said.

Iran’s forces there support President

Bashar al-Assad,

who with the help of Iran and Russia is trying to fend off a challenge from U.S.-backed rebels and Islamic State militants. Iranian-backed Shiite militias, like the U.S., are also opposed to Islamic State.

said the Israeli strikes hit nearly all Iranian infrastructure in Syria. “[The Iranians] have to remember,” he told a policy conference, “if for us it’s raining, it will be a flood for them.”

Iranian officials have yet to respond, but the Islamic Republic has used small-scale attacks before to needle Israel, which alongside the U.S. is considered a bitter enemy. In February, Israel said an armed Iranian drone strayed across its northern border before Israeli forces shot it down in an incident that ended with the downing of an Israeli jet.

Without referring specifically to the Israeli attacks, Brig.

Gen. Hossein Salami,

the deputy commander of the IRGC, boasted Thursday that Iran had become deeply influential in Syria.

“We will expand our deterrent and defensive power, and will not disarm ourselves against our enemies,” said Mr. Salami, according to the official Islamic Republic News Agency.

Iran is expected to punch back, said

Reza Marashi,

the research director at the National Iranian American Council, but officials will first have to assess the damage and formulate a strategy. Iran would likely also consult with Russia before making any moves, he said, so as to avoid losing a crucial leg of support.

“My concern is I don’t see what the off-ramps are,” he said. “I liken it to a car driving down the freeway and there’s a cliff at the end that goes into the ocean, and there’s no exit. If we don’t build off-ramps quickly, we’re going to fall off a cliff.”

Syrian state media reported its forces shot down dozens of Israeli missiles. The Israeli military said it faced Syrian aerial defense fire and in response targeted several aerial interception systems that belong to the Syrian military.

The Syrian regime has sought to project strength, even as its military forces have been drained and it has relied on Iran and Russia. Pro-regime media Al-Masdar News reported that while the Syrian military did “the bulk of the work, the Iranian forces… are believed to be participating in these retaliatory strikes against Israel.”

Intelligence officials have estimated that Iran works from five airfields in Syria. At each, Iranian military transport aircraft bring weapons for Hezbollah or missiles and drones specifically for Iranian forces, these officials said. The intelligence officials also said there is a Quds Force command center at the Aleppo Airport.

“Iran’s presence and activities in Syria have nothing to do with protecting the sovereignty and territorial integrity of Syria,”

Brett McGurk,

the U.S. envoy to the fight against Islamic State, told a conference in Israel on Thursday. “Iran’s presence risks a wider conflict that would mire Syria in ongoing turmoil for months and years to come.”

Some allies have urged against any escalation of hostilities. On Thursday, French President

Emmanuel Macron

discussed the air strikes with German Chancellor

Angela Merkel,

an aide to Mr. Macron said, adding that both leaders expressed worry and called for a de-escalation in tensions.

Russian news agencies quoted Deputy Foreign Minister

Mikhail Bogdanov

as saying there should be efforts to de-escalate. “We have developed contacts with all sides and we are indeed calling for restraint,” agencies quoted Mr. Bogdanov as saying.

Russia wants to avoid a broader confrontation that would upset the careful balance of interests Russia has relied on to become one of the most important actors in the conflict.

Mr. Bogdanov said the strikes were brought up during Prime Minister

Benjamin Netanyahu’s

visit to Moscow this week for Russia’s commemoration of the Soviet Union’s triumph over Germany in World War II. Israel informed Russia prior to carrying out the strikes, the Israeli military said.

—Thomas Grove in Moscow, Raja Abdulrahim in Istanbul and Stacy Meichtry in Paris contributed to this article.

Write to Asa Fitch at asa.fitch@wsj.com and Felicia Schwartz at Felicia.Schwartz@wsj.com